Alarm scanner apparatus and method

ABSTRACT

A high speed scanning system and method for scanning a matrix of alarm condition sensing means. A clock-fed counter means and decoder means automatically scan the matrix line by line. When a sensing means which has turned on due to the detection of an alarm condition is sensed the scanning means automatically stops scanning and a readout of the matrix position of the triggered alarm sensing means is provided. The scanning operation may be controlled in either an automatic mode by a central porcessing unit or in a manual mode by switches located on a control panel. The scanning operation may be stopped or started, the counters may be cleared or loaded and the current scanned matrix position may be read out.

United States Patent [191 Houston et al.

[ ALARM SCANNER APPARATUS AND METHOD [75] Inventors: Randie M. Houston,Fairfax; Harold G. Wilson, Jr., Woodbridge, both of Va.

[73] Assignee: Computer Sciences Corporation, El

Segundo, Calif.

[22] Filed: May 16, 1974 [21] Appl. No.: 470,681

[52] US. Cl. 340/166 R; 340/163 VERTICAL DECODER 51 Nov. 18, 19753,651,463 Rawson 340/166 R [57] ABSTRACT A high speed scanning systemand method for scanning a matrix of alarm condition sensing means. Aclock-fed counter means and decoder means automatically scan the matrixline by line. When a sensing means which has turned on due to thedetection of an alarm condition is sensed the scanning meansautomatically stops scanning and a readout of the matrix position of thetriggered alarm sensing means is provided. The scanning operation may becontrolled in either an automatic mode by a central porcessing unit orin a manual mode by switches located on a control panel. The scanningoperation may be stopped or started, the counters may be cleared orloaded and the current scanned matrix position may be read out.

10 Claims, 3 Drawing Figures HORIZONTAL MULTIPLEXER. R" OUTPUTMULTIPLEXER ADDRESS LEADS U.S. atent FROM MULTIPLEXER BINARY COUNTER.

Nov. 18, 1975 3,921,140

Sheet 2 0f 4 ADDRESS LEADS CARRY BINARY CARRY COUNTER.

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FLIP-FLOP R US. Patent Nov. 18, 1975 Sheet 3 GM n39 fib {Fl-C40 LOAD 5.360 i 7% 32 .1. Q f4z 54 6/ Cr43 a? AUTO. 67 O i MAN. 0 45 -Q 48CLEAR 57w 50 START 58 -Q 52 STOP 59 E L 66 4 2a -73 INTERRUPT J CENTRAL T"PROCESSING UNIT US. Patent Nov. 18,1975 Sheet4 of4 3,921,140

ALARM SCANNER APPARATUS AND METHOD speed matrix scanning system andmethod.

The scanning system of the invention finds special application in thehigh speed scanning of alarm sensors which is necessary in modern alarmmonitoring installations. Such installations are frequently called uponto continuously monitor large numbers of remotely located alarm sensors.For instance in a large complex of buildings or in a subway system theremay be a large number of alarm sensors for sensing different alarmconditions located remotely from each other. According to the inventiona high speed scanning system for providing a continuous indication ofthe states of all of the alarm sensors is provided.

It is thus an object of the invention to provide a selectable speed,high speed matrix scanning system and method.

It is a further object of the invention to provide a system for thecontinuous monitoring of the states of a large number of remotelylocated alarm sensors.

According to the invention a matrix of alarm sensing means is providedwhich means change state when an alarm condition is detected. Countingand decoding means are provided to sequentially scan the matrix in lineby line fashion and a means for automatically stopping the scanning whenan alarm condition is sensed and for reading out the address of thetriggered sensing means is provided. An adjustable clock feeds clockpulses to the counting means and the scanning speed may be controlled byadjusting the frequency of the clock.

BRIEF DESCRIPTION OF THE DRAWINGS A better understanding of theinvention may be had by referring to the following drawings in which:

FIG. 1 is a drawing of the scanner matrix and the horizontal andvertical decoders.

FIGS. 2 and 2A comprise a diagram of the control logic for controllingthe scanning of the matrix.

FIG. 3 is one embodiment of block 2 of FIG. 1.

FIG. 4 is a schematic diagram of block 6 of FIG. 1.

FIG. is a schematic diagram of block 5 of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION A matrix 1 shown in FIG. 1 iscomprised of vertical busses 3 and horizontal busses 4 and plurality ofalarm sensing means 2 the number of which corresponds to the number ofcross-over points of the matrix.

One embodiment of the alarm sensing means 2 is shown in greater detailin FIG. 3 and are seen to comprise base-driven transistor switches.Thus, referring to FIG. 3, the emitter of transistor 78 is connected toa vertical while the collector of the transistor is connected to ahorizontal. The base of the transistor is connected to terminal 75through diode 76 and resistor 77. Each terminal 75 of the matrix isconnected to a source of voltage which is switched on when an alarmcondition is detected. Thus each terminal 75 would be connected to analarm sensor which for instance could be a thermistor, photocell, etc.and the plurality of alarm sensors could for instance all be at remotelocations.

The alarm sensors would be connected in known circuit arrangements sothat when an alarm condition was detected a voltage would appear atterminal 75 thereby turning transistor 78 on and connecting together thehorizontal and vertical between which the transistor is connected.

In an alternative embodiment block 2 may comprise aphototransistor/light emitting diode combination wherein the emitter andcollector of the phototransistor would be connected as shown in FIG. 3.The base of the phototransistor would be driven by a light emit tingdiode which would be connected in known circuit arrangement with analarm sensor so that the light emitting diode is energized when an alarmcondition is present which is effective to turn the phototransistor onthereby connecting together the horizontal and vertical to which it isconnected. The advantage of this embodiment is that superior electricalisolation is achieved between the alarm sensor and the phototransistor.

SCANNING THE MATRIX The matrix is scanned to determine the conditions ofthe various alarm sensing means by selecting each vertical element ofthe matrix in turn and for each vertical element sequentially steppingthrough each of the horizontal elements before the next vertical elementis selected. Of course in the alternative the vertical elements could hestepped through while each horizontal is selected and scanning canproceed either in the rightleft, left-right, downup or up-downdirections. Each vertical element is connected to an isolationtransistor unit 6 shown in schematic diagram form in FIG. 4. In FIG. 4it is seen that the collector of transistor 79 is connected to thevertical element while the emitter thereof is connected to. ground. Aparticular vertical element is selected by driving the base oftransistor 79 through buffer 7 and resistor 80 thereby turning thetransistor on and connecting the vertical element to ground. Thehorizontal elements are selected through horizontal isolation transistorunit 5 shown in greater detail in FIG. 5. Isolation transistor unit 5 iscomprised of transistor the emitter of which is connected to ground andthe base of which is connected to resistors 83 and 84, the collectorbeing connected to resistor 82. Terminal 81 is connected to a source ofpositive voltage as shown in FIG. 1.

The horizontal elements are selected by multiplexer 9 which in turnconnects each of the conductors 86 to multiplexer output line 30. Achange in voltage on line 30 will occur when a row-column cross-overpoint is scanned having a turned on alarm condition sensing transistorconnected therebetween. This is because the selected column of theselected row-column combination will be connected to ground throughisolation transistor unit 6. Further the selected column element will beconnected to the selected row element through switch means 2 meaningthat base resistor 84 of the selected row will be connedted to groundthereby changing the voltage at the collector of transistor 85 whichchange in voltage is fed to multiplexer output line 30. Hence, each timea scanned alarm sensing means is in the on condition a change in voltagewill occur on output line 30. While in the embodiment shown the changeis an increase in voltage which causes the reset input of flip flop 13to go high the system would also be designed so that the change involtage on line 30 indicating an alarm condition'is a fall in voltage.

In a preferred embodiment of the invention 16 horizontals are used andup to 512 verticals, resulting in 8,192 scanning points. Preferably, thebusses are arranged on matrix cards and the matrix is expanded by addingcards. As is apparent to those skilled in the art, any number ofhorizontal or vertical elements may be used and the invention is notlimited to the numbers mentioned above.

THE CLOCK AND ADDRESSING SYSTEM Referring to FIGS. 2 and 2A,, clock isemployed which may be an astable multivibrator or other freerunningclock as known to those skilled in the art. The clock rate of clock 10will determine the scanning speed of the system and the rate may beadjusted as appropriate for a given system. The output of clock 10 isfed to AND gate 11 the other input of which is the set output ofset-reset flip flop 13. When the scanning operation is in progress theset output of flip flop 13 is high and gate 11 will gate the clockoutput pulses of clock 10 through to the input 91 of binary counter 15.Binary counters 15, 16, 17, and 18 are arranged in a cascade as shown toprovide the address counts for vertical and horizontal decoders 8 and 9.The address signals are connected through buffer 19 to the decoders andthe rightmost group of address leads in FIG. 2 corresponds to thetopmost group of leads shown in FIG. 1 and so on for the other groups ofleads. Each address lead is connected to an illumination device 20 suchas for instance a light-emitting diode which would be located on amaintenance panel. The four bits fed to horizontal decoder 9 can carry16 counters to the decoder corresponding to the 16 horizontal elements 4shown in FIG. 1 while the 9 bits fed to vertical decoder 8 can carry 512counts. Thus if all counts are utilized the illustrated system can scana matrix of 512 X 16 or 8,192 scanning points.

The horizontal decoder 9 decodes the 16 counts on the 4 lines fed to itand for each of the counts connects one of 16 lines 86 to multiplexeroutput line 30. For instance unit 9 may comprise a decoder havingsixteen output lines in combination with a multiplexer which may becomprised of sixteen normally closed transistor switches connecting eachof the lines 86 to line 30. Each of the decoder outputs would beconnected to switch on a different of the transistors in succession sothat each of lines 86 would be successively connected to output line 30.The vertical decoder 8 can have up to 512 output lines and decodes thesignals appearing on the 9 lines inputted thereto to sequentiallyactivate a new vertical element every 16 counts. Each vertical column isthus selected in succession and held for 16 counts during which time the16 horizontals are scanned. The count rate is determined by the outputfrequency of clock 10 and scanning system is free run- T he scanner willcontinue to automatically scan the matrix column by column in a freerunning fashion until an alarm sensing means 2 in the on state isdetected at which time a signal will appear on multiplexer output linewhich signal is fed through one-shot multivibrator 12 on OR gate 14 tothe reset input of flip flop 13. This will cause the reset output offlip flop 13 to go high and the set output to go low thus causing gate11 to inhibit the clock signals applied thereto from clock 10 andcausing the scanning operation to stop at the matrix position of theturned on alarm sensing means.

AUTOMATIC OR MANUAL MODE The scanning system of the invention may beoperated in either an automatic mode or in a manual mode, which wouldcustomarily be used for testing or maintenance. The switches 60 to 66and the illumination means 20 are located on a control panel and wouldbe utilized in the manual made. In the automatic mode a centralprocessing unit 74 which may comprise'a minicomputer would be used. Thecentral processing unit provides routine stop, start, sample, etc.commands to the scanning system and the programming of these commands iswithin the skill of one in the art. In FIG. 2A terminals 68, 69, to 73and 88 are interfaced with central processing unit 74. 7

When the processing unit'74 is controlling operation of the system,switch 67 is switched to the automatic position which is tied to avoltage of 5 volts. This voltage is connected by line 87 as one of theinputs to AND gates 39, 41, 43, 45, 47, 49, 51, and also 38. Hence whenthe reset output of flip flop 13 goes high in response to the detectionof an alarm condition the signal is gated through gate 38 and is appliedat terminal 73 to the interrupt input of central processing unit 74.Processing unit 74 then issues a command to sample lines 68 which isconnected to the output of binary counters 15, 16, 17 and 18 todetermine the matrix position of the turned on alarm sensing means. Thuswhen the processing unit is interrupted it reads the 13 bit addresswhich is frozen on lines 68, stores the address and sends back a startcommand at terminal 71, which command is fed through OR gate 36 to setflip flop 13 once again and again allow the clock pulses to pass throughgate 11 to resume the counting and the scanning of the matrix where itleft off.

The free-running scan continues until another alarm condition is foundor until the end of the matrix is encountered. The decoder address forthe last column is set as an alarm condition by applying a positivevoltage to the highest horizontal level on the last vertical row,assuming a down to up direction of scanning. When the end of scan alarmpoint is noted by the central processing unit it provides a clearcommand signal at terminal 70 which is fed to clear inputs 21, 22, 23,and 24 of counters 15, 16, 17, and 18 respectively to clear the countersand return the scanner to its initial position, the alarm sensing meansof which is wired permanently off so the position serves as a restposition. The processor may then peforrn an independent chech todetermine if any alarms have cleared during the previous scan. When thecheck is complete the processor provides a start command at inputterminal 71 which is applied through OR gate 36 to set flip flop 13 andbegin the clock running and the counters counting again. When thecentral processing unit requests the condition of a particular point inthe matrix a command signal is inputted at terminal 72 to reset flipflop 13 and stop the scanner, the current address is read at terminals68 and the address to be selected is transferred to the counter byinputting a command signal to terminal 88 which is fed to load inputs25, 26, 27, and 28 of counters 15, 16, 17, and 18 respectively to allowthe counters to be parallel loaded. The proper number to be loaded intothe counters is determined on the basis of the desired address and thecurrent address read from terminals 68 and this number is loaded intothe 13 parallel load input of the counter by appropriate activation ofinput terminals 1 through 13 of terminal group 69 which performs aparallel load of the 13 bit counter causing selection of the desiredscanning point.

Manual operation of the scanning system is effected by switching switch67 to the manual position which ties the switch to ground. The other endof the switch is connected to line 87, which is connected to AND gates40, 42, 44, 46, 48, 50, and 52 through invertors 53 to 59 respectively.Hence appropriate manual closure of switches 60 to 66 is effective tostart, stop, clear or load the system in the same manner as described inconjunction with automatic operation and illumination means 20 at alltimes visually indicate the matrix point being scanned.

While we have disclosed and described the preferred embodiments of ourinvention, we wish it understood that we do not intend to be restrictedsolely thereto, but that we do intend to include all embodiments thereofwhich would be apparent to one skilled in the art and which come withinthe spirit and scope of our invention.

We claim:

1. Apparatus for detecting the presence of alarm conditions comprising amatrix of alarm sensing means which change state when an alarm conditionis sensed, said matrix comprising a set of horizontal conductingelements and a set of vertical conducting elements, said alarm sensingmeans corresponding to each cross-over point of said elements, each ofsaid sensing means corresponding to a matrix crosspoint including switchmeans connected between the horizontal and vertical elements whichdefine matrix crosspoints, means, including counting means, forsequentially scanning said sensing means at each of said matrixcrosspoints, means responsive to a scanned sensing means being in saidchanged state for stopping said scanning at the matrix crosspoint atwhich a change state occurs and providing a readout of the position insaid matrix of said changed state sensing means, and means for startingsaid scanning again after said readout has occurred.

2. The apparatus of claim 1 further including means for stopping saidscanning independently of the state of said sensing means and means forloading said counting means to cause the state of a desired sensingmeans to be detected.

3. The apparatus of claim 2 further including means for clearing saidcounting means.

4. The apparatus of claim 1 wherein said scanning means includes amultiplexer means connected to one of said sets of conducting elementsfor sequentially outputting signals indicative of the state of saidsensing means, said means responsive to a scanned sensing means being insaid changed state being responsive to the output of said multiplexermeans, said means for scanning further including a clock means which isconnected to activate said counter means, and said means for stoppingincluding a switch means responsive to the output of said multiplexermeans for stopping said clock means.

5. The apparatus of claim 1 further including a plurality ofillumination means being connected to the outputs of said counting meansto visually indicate the position of the sensing means being scanned.

6. The apparatus of claim 1 wherein said means for scanning furtherincludes horizontal and vertical decoder means, the inputs of which areconnected to the outputs of said counting means, and the outputs ofwhich are connected to said horizontal and vertical conducting elementsrespectively for effecting line by line scanning.

7. The apparatus of claim 5 wherein said readout is accomplished bysampling the outputs of said counting means.

8. A method of detecting which of the alarm condition sensing means of arow-column conductor matrix of said sensing means is in the alarmindicating state wherein said alarm condition sensing means areconnected at row-column crosspoints of the matrix, there being one alarmcondition sensing means at each crosspoint, comprising the steps ofsequentially scanning said sensing means in column by column fashion,each crosspoint of a given row being scanned in sequence,

stopping said sequential scanning when a sensing means in the alarmindicating state is detected,

providing an indication of matrix crosspoint position when saidsequential scanning is stopped, and

starting said scanning again after said indication has been provided.

9. In a cross-point matrix system, apparatus for sampling individualcross point conditions of a plurality of cross points in a row-columnmatrix comprising,

1. a sensed condition output means,

2. automatic scanning means connected to said rowcolumn matrix array forsequentially scanning said cross points and the conditions thereat froma starting cross point to an end cross point and terminating saidscanning at any cross point at which a change signal condition from agiven condition is present and connecting said any cross point to saidsensed condition output means said automatic I scanning means, includinga multiplexer connected to receive signals from all conductors of one ofthe conductor axes of said row-column matrix and means forsequentiallyenergizing the conductors in the other axes,

3. a manually actuated matrix cross point selection signalling meansconnected to said row-column matrix for I a. terminating the automaticscanning of said rowcolumn matrix, and

b. generating a signal representing the manually selected cross point ofsaid row-column matrix and connecting said cross point manually selectedto said sensed condition change output means, and

4. a remotely actuated automatic matrix cross point selection signallingmeans connected to said rowcolumn matrix for a. terminating theautomatic scanning of said rowcolumn matrix, and

b. generating a signal representing the remotely selected cross point ofsaid row-column matrix and connecting said remotely selected cross pointto said sensed condition change output means.

10. The apparatus of claim 1 wherein said solid-state switch meanscomprises a phototransistor.

1. Apparatus for detecting the presence of alarm conditions comprising a matrix of alarm sensing means which change state when an alarm condition is sensed, said matrix comprising a set of horizontal conducting elemenTs and a set of vertical conducting elements, said alarm sensing means corresponding to each cross-over point of said elements, each of said sensing means corresponding to a matrix crosspoint including switch means connected between the horizontal and vertical elements which define matrix crosspoints, means, including counting means, for sequentially scanning said sensing means at each of said matrix crosspoints, means responsive to a scanned sensing means being in said changed state for stopping said scanning at the matrix crosspoint at which a change state occurs and providing a readout of the position in said matrix of said changed state sensing means, and means for starting said scanning again after said readout has occurred.
 2. The apparatus of claim 1 further including means for stopping said scanning independently of the state of said sensing means and means for loading said counting means to cause the state of a desired sensing means to be detected.
 2. automatic scanning means connected to said row-column matrix array for sequentially scanning said cross points and the conditions thereat from a starting cross point to an end cross point and terminating said scanning at any cross point at which a change signal condition from a given condition is present and connecting said any cross point to said sensed condition output means said automatic scanning means, including a multiplexer connected to receive signals from all conductors of one of the conductor axes of said row-column matrix and means for sequentially energizing the conductors in the other axes,
 3. a manually actuated matrix cross point selection signalling means connected to said row-column matrix for a. terminating the automatic scanning of said row-column matrix, and b. generating a signal representing the manually selected cross point of said row-column matrix and connecting said cross point manually selected to said sensed condition change output means, and
 3. The apparatus of claim 2 further including means for clearing said counting means.
 4. a remotely actuated automatic matrix cross point selection signalling means connected to said row-column matrix for a. terminating the automatic scanning of said row-column matrix, and b. generating a signal representing the remotely selected cross point of said row-column matrix and connecting said remotely selected cross point to said sensed condition change output means.
 4. The apparatus of claim 1 wherein said scanning means includes a multiplexer means connected to one of said sets of conducting elements for sequentially outputting signals indicative of the state of said sensing means, said means responsive to a scanned sensing means being in said changed state being responsive to the output of said multiplexer means, said means for scanning further including a clock means which is connected to activate said counter means, and said means for stopping including a switch means responsive to the output of said multiplexer means for stopping said clock means.
 5. The apparatus of claim 1 further including a plurality of illumination means being connected to the outputs of said counting means to visually indicate the position of the sensing means being scanned.
 6. The apparatus of claim 1 wherein said means for scanning further includes horizontal and vertical decoder means, the inputs of which are connected to the outputs of said counting means, and the outputs of which are connected to said horizontal and vertical conducting elements respectively for effecting line by line scanning.
 7. The apparatus of claim 5 wherein said readout is accomplished by sampling the outputs of said counting means.
 8. A method of detecting which of the alarm condition sensing means of a row-column conductor matrix of said sensing means is in the alarm indicating state wherein said alarm condition sensing means are connected at row-column crosspoints of the matrix, there being one alarm condition sensing means at each crosspoint, comprising the steps of sequentially scanning said sensing means in column by column fashion, each crosspoint of a given row being scanned in sequence, stopping said sequential scanning when a sensing means in the alarm indicating state is detected, providing an indication of matrix crosspoint position when said sequential scanning is stopped, and starting said scanning again after said indication has been provided.
 9. In a cross-point matrix system, apparatus for sampling individual cross point conditions of a plurality of cross points in a row-column matrix comprising,
 10. The apparatus of claim 1 wherein said solid-state switch means comprises a phototransistor. 